Centralized traffic controlling system for railroads



July 28, 1936. c. s. BUSHNELL CENTRALI ZED TRAFFIC CONTROLLING SYSTEM FOR RAILROADS Filed Jan. 2, 1932 5 Sheets-Sheet 1 ATTORNEY ft Em 21$ m 115 Jui y 28, 1936. c. s. BUSHNELL CENTRALIZED TRAFFIC CONTROLLING SYSTEM RAILROADS Filed Jan. 2, 1932 3 Sheets-Sheet 2 XT J J July 28, 1936. c. s. BUSHNELL 2,049,406

'CENTRALIZEDYTRAFFIC CONTROLLING SYSTEM FOR RAILROADS Filed Jan. 2, 1932 s Sheets-Sheet 3- ATTORNEY n u m w 8 u no u n +Qmu k I u 83w w NM. MW MW. u mw 2 Pl 3 m ZOHFSPM Q 5ml FWNEL Patented July 28, 1936 UNITED STATES CENTRALIZED TRAFFIC CONTROLLING Y SYSTEM FOR RAILROADS Charles S. Bushnell, Rochester, N. Y., assignor to General Railway Signal Company, Rochester,

Application January 2, 1932, Serial No. 584,428

44 Claims.

This invention relates to centralized traflic control systems for railroads and more particularly to av means for communicating between a central control point and various points along the railroad whereby an operator can govern trafiic controlling devices in the system and can receive indications of the operated position of such traffic controlling devices as well as the progress of trains throughout the particular territory of the system. 1

In a centralized traffic control system, an operator at a central control point is able to govern trafiic movements throughout the territory of the system by supervising the operation of traffic controlling devices thereof. Power operated track switches are usually employed with local approach locking and like means to prevent the movement of these switches in case the operator directs a movement of the switch at a time when traffic conditions make such a switch movement unsafe. The signals, in such a system, are likewise automatically controlled in accordance with local conditions such as the location of trains and the position of switches, yet these signals are under the supervisionof the operator inasmuch as he can hold them at stop regardless of their automatic controlor he can allow them to clear if their automatic control allows such a clear indication.

The present invention relates to such a system which involves the features of an automatic.

block system, such as disclosed for example in the application of S. N. Wight, Ser. No. 120,423, filed July 3, 1926, together with a communicating system which enables the operator to supervise train movements by conditioning switches and signals and thus eliminate the use of train orders. The features of the present invention reside more particularly in the communication means that is, the means by which the operator can,.at will, select and control a particular traificcontrolling device and also the means by. which any change in condition of traffic controlling devices or position of trains on the system may distinctively register itself at the control'point.

In the communication system of this invention, such trafiic controlling devices and circuits which are closely associated may be grouped together to constitute the equipment of a field station. Such a field station may include means suitable for governing the operation of a track switch and associated signals and for indicating the position of the switch, conditions of the signals, the condition of trackcircuits or such associated controls and indications as may be desirable in the particular application.

The transmission of controls to the several field stations in the ,proposed communicating system is accomplished over a single circuit ex- '5 tending to all such field stations of the system and the selection of a particular field station is accomplished by allotting a distinctive code call to each station and impulsing the aforesaid circuit with a particular code call effective to select 10 the corresponding station. The field stations may in a similar manner distinctively register themselves at the control point, one at a time,- by impulsing the same circuit with the distinctive code calls allottedthereto.

After the selection of such a field station, a continuation of the coded impulses transmits the selected controls to the selected field station and likewise after a field station registers itself at the control point, a continuation of the coded 20 impulses transmits the indications of that field station to associated apparatus at the control point.

The present invention also proposes to provide distinctive coding means by periodically energizing the aforesaid single circuit with a choice of two distinctive impulses of energy, such impulses being distinguishable by the degree of energization. thereof.

. A further object of the present invention is to provide a communicating system with a single communicating circuit as above mentioned normally energized from a single source of energy at the central control point with a relatively low value, of current, which communicating system may be initiated into. operation from the control point by momentarily energizing this communicating circuit with a higher value of current.

A still further object of the invention is to enable any field station to initiate operation of the communication system by opening this circuit thereby locking out all other field stations until completion of this operation with provision against simultaneous initiation of the communication system by several stations by granting superiority to the field-stations in accordance with their location relative to the control point.

Other objects, purposes and characteristic features of the present invention will appear as the, description thereof progresses, during which reference will be made to, the accompanying drawings; in which similar parts throughout the several views are designated by like reference characters provided with distinctive exponents, and.in.which:

Fig. 1 shows the apparatus and circuits for a control ofi'ice in accordance with this invention. Fig. 2 shows the apparatus and circuits for a typical field station having a distinctive code call.

Fig. 3 shows the arrangement of the line circuit of the present invention.

The system illustrated in the accompanying drawings has been shown in as simple and diagrammatic manner as possible in order to clear.- ly explain the principles and operations thereof without attempting to show the particular arrangement perferably employed in practice.

All functions of the present system are performed by relays which are shown with their wire connections in a conventional diagrammatic manner and symbols are used to indicate sources of -energy instead of extending all wire connections to the actual energy sources except the single source of energy for the communieating circuit which is indicated as a battery B. These relays may be of the telephone type and certain ones, it will be noticed, are of the polarized magnetic stick type which remain in either of their operated positions; while the majority of the relays employed are of the neutral tractive armature type. Some of such neutral relays have twoindependent windings andothers have slow acting characteristics which are indicated by having heavy base lines;

The general system layout is shown in Fig. 3 and consists essentially of a single two wire circuit originating and energized at a central point or control ofiice and extending to all field stations of the system, which. circuit is normally completed by connecting together the two line Wires at the last station. A neutral relay LH which responds only to a high degree of energization and a second neutral relay LL which re sponds to either a high or a low degree of energization are included in series with the line circuit at each field station as well as'at the control ofiice. In other words, the relay LL may be provided with a greater number of turns on its operating winding than relay LH and this-ratio of turns will substantially be determined by the ratio of the current of a high impulse to that of a low impulse.

A resistor R at the control ofl ice'is arranged to limit the energization of the line to a low degree when the system is not in operation or during a period of blank.- This resistor R is disconnected during operation by a contract of a relay ST which then makes thedegree of energization of the line selectable by a second resistor R which is shunted by a contact of a. relay SEL except when the control office iscalling a'station at which time it may be either shunted or uncovered by a contact of a code selecting relay CS to determine the degree of energization of each line impulse. A pulsing relay P is also included at the control ofiice and is arranged to periodically energize the line during operation as will be more fully described hereinafter.

Each field station has a relay LO arranged to interrupt the line at a point in the circuit beyond the two series line relays LH and LL of that station whenever that field station is transmit!- ting indications to the control office, thereby locking out such other stations as may be located more remotely with respect'to the control office.

The relay LO inaddition to breaking the line circuit beyond any field station also completes the line from that station to the control ofiice by shunting the line wires at that station. This shunt at each station includes a front contact of an SA relay and a resistance RF. This resistor RF may be shunted or uncovered by a contact of a local code selecting relay OS to select the degree of energization of the line impulses in accordance with the codes to be transmitted. A line voltage adjusting resistor RA is included at each field station in the shunt completed on the line at that station by the picking up of the LO relay. The function of these resistors is to equalize the voltage on the series line relays of the circuit for the various field stations inasmuch as the lengths of the included line circuit varies according to the location of the communicating station from the control offifce; This line circuit arrangement is identical for each station of the system and, as shown in Fig. 3, the line wires are connected together at the last station;

Control oflice equipment-The control oflice equipment includes such conventional manual- 1y operable means corresponding to each field station as will enable an operator to setup distinctive conditions therewith, which conditions may be efi'ective to control various traffic controlling devices at the particular field station. The oflice equipment also includes such indicating means, preferably associated with a miniature track diagram, as will convey information concerning the operated positions of tramc controlling devices and the occupied or unoccupied condition of various tracksections in the system. All these controls may be arranged in any convenient manner which will insure the most efficient control of traffic throughout the system. In this disclosure no attempt has been made to show all such parts and their arrangements, but suitable manual controls for a single field station have been shown diagrammatically astypical of other traific controlling devices.

These controls, as shown in Fig. 1, may be such as control lever SML which is operable to two distinct positions to operate suitable contacts which set up controls for a single track switch. A signal control lever SGL is similarly shown and may be movable to any one of three positions and. is for the control of the signals and traific direction over the single track switch.

The means for displaying the above mentioned indications may be small lights, such as lamp I in Fig. 1',' which is shown as indicating the occupancyof a track sectionand similar means may bearranged for other desirable indications. The control leversas well as the indicating means are preferably, associated with a miniature track diagram of the system.

A storing relay SR and a code, determining relay ,C'D, one;of each for each field station, are included at thecontrol ofiice which are selectively energized to condition the control ofiice for transmitting the Station selecting and control codes. The control of the storing relays SR and the interlocking of the CD relays is contemplated to be the same as similar relays fully described in the prior application of W. D. Hailes and D. F. DeLong, Ser. No. 526,674, filed March 31, 1931 .and consequently will not be fully described herein.

A bank of stationregistering relays is included I ble the registration, at one time, of any one of three different field stations by selectively energizing either relay C C or C It is obvious that with two impulses four difierent codes are obtainable but for reasons later described only -three stations are selected. Also, it is obvious that any number of stations may be selected by employing the proper number of impulses or steps, but to simplify the disclosure only three stations are considered. After the selection of one of the relays the remaining impulses of the cycle, as previously described, are utilized to transmit the indications to the indication storing means associated with that station.

A suitabie number of stepping relays are also included and arranged to be energized sequentially, one at a time, by impulses applied to the line crcuit. The number in the present embodiment is illustrated as five stepping relays a, b, c, d and 2, two of which are employed for station selection and registration and the other three for transmission of controls and indications.

The imp-ulsing relay P, which as previously mentioned functions to periodically energize the .line circuit, is arranged in combination with the stepping relay bank to be selectively energized thereby. Also, associated with the stepping relay bank is a half step relay SP arranged, as later described, to energize the relays of the stepping bank one at a time in response to their impulses.

A slow acting cycle demarcating relay SA, a starting and stopping relay ST, a slow acting repeating relay STP, and a selecting relay SEL are also included at the control ofiice. The code of each step is determined, as previously mentioned, by the relay C5 which is energized by contacts of the stepping bank according to the station selecting code and controls which are selected to be transmitted.

Field station equipment.The grouping of various tramc controlling devices into field stations is determined by the particular arrangement and location of such devices but as illustrated in the field station equipment of Fig. 2, a group will be considered as a single track switch TS power operated by a switch machine SM with signals SE and SE governing movements in one direction and signals SW and SW governing movements in the other direction thereover. The apparatus and circuits necessary to establish communication between a field station and the control office is the same for each station, the only difierence being that certain distinctive connections are made at each station to render it responsive to a particular code call assigned thereto.

The station selecting apparatus for the field stations is similar to that of the control office except that, inasmuch as the line circuit is intermittently energized at the control office by the pulsing relay P a similar relay is not necessary at the field station. A slow acting relay SAP is included to repeat the position of the relay SA which then functions in a stick circuit of the relay LO'as will'be later described. The same number of stepping relays are employed at the energized sequentially one at a time in synchronism with the stepping relays at the control ofiice and similar pilot relays PT and PT are arranged to be selectively energized or de-energized' respectively by the character of the first two impulses. Through these relays a station may be selected and the circuit completed through their contacts to respectively position-function relays SMR, 'SG and DR. by the character of the remaining impulses of the cycle. The function relay SMR is of the two-position polarized type and is employed to control a switch machine SM, such as disclosed for example, in the patent to W. K. Howe, Patent No. 1,466,903 dated September 4, 1923 which is also subject to conventional detector locking and approach locking means such as disclosed in Patent No. 2,038,463 granted April 21, 1936 which thus prevents unsafe operationof the switch points. The function relay SG is arranged to allow the signals at this station tobe cleared or cause them to be held at stop, while the position of the function relay DR selects the direction of trafiic by clearing the proper signals for the route selected by the track switch. 7

The field station equipment also includes a change relay CH and a change storing relay CHS which relays are arranged to register the existence of any new indications to-be transmitted to the control oiiice. These new indications are determined by contacts distinctively actuated in accordance with local conditions which were previously mentioned. The variousrelays, wire connections and other apparatus of each field station may be arranged in a unit cabinet which cabinet, because of the similarity of all field station equipment as well as'the control ofiice equipment, may be constructed as an interchangeable unit to which suitable jumpers and external connections are added toindividually adapt it to its particular part in the system. .Various other auxiliary equipment such as wire terminals, lightning protective means and other necessary equipment which is customary in railway signallingpractice are also included at both the control ofiice and field stations but have been omitted to simplify this disclosure.

Operation of the syste'm.It is believed that the characteristics and functions of the present system can best be pointed out by further discussion of the various operations through which the system functions under the difierent conditions. The line circuit, as briefly described, when the system is at rest or in a period of blank, is energized to a low degree of energization and the position of the relays of the system at such time is as shown in the accompanying drawings. The initiation of operation of this system to transmit new controls from the control oftlce may be accomplished by the movement of any control lever, or operation may be automatically initiated at any field station having new indications to transmit to the control office, but in either case the system operates through what is termed an operating cycle and then returns to its normal at ner which; is found desirable,

of he. same number-end di ide into twoparts.

oeh h en l e med e se ec i or re isteri Pa t and a r n mittin o comm nica in part...v the; ease o a on r iii a he first part g. f; t e yc e t hepartioular fie d station.

ith. hi h e mmun t o iis. t be held; and: the. e ond rt. is he a ua ommun ca on w ich;

the a show is h t nsm sion or; newcontrols to the selected station. In a similar 9; ma er h d. Station cycle e isters. he 122:

tion itself at the control ofilceon the first part of;

the cycle and transmits its new indicationson the remaining part of the cycle.

In describing the operation of the system in &5 etai te c n n o i c ss t e seve a s ouos:

f operat ons nd d a under separ t head.-

hee fir t exbl nihe; he transmiss n; i con ro s; rom th oon r l' flioed cond he m an o the ommunica ion o new in at s om. he

212.; field stations and finally the operation of the system to lock out all but one field. station when, more than one of such stations have new indications to transmit.

M anuaZstarting.-When the system atrest 25.:the operator'may start the transmission of conro s o. a fie d. s ion by m ng the c e ch. a. re ie controlling. d c as b may; desire to operate. In the particular embodiment shown in F le. 1, it is obvious that the movement of either control lever SML or- SGL from one-position to another momentarily opens the stick circuit for the storing relay SR which; is thereby caused to assume a de-energized position. stick circuit may be traced from 5;.Tcontact Q or lever SGL in anyextrerne position,

either wire 1 or 8, contact 3 of lever SML in ith r s tion, r r n c tac 1. o 'r la W 1.2, e ay S to The ner n ir i e st ies ela s 49. S d h m ans in whi e de ehe iz n or:

the o in re ay o he yste is effective ener iz correspondin ode de m nin re ay CD i no s wn in h d o o urebilt ma e.

learl nders ood b ref rin o. hen or p iicati n of W- Heiles a DeLo e, Se

N 26.674; le Ma c 3 .3. w e a lea yi sh ws an d e ibe h a ran me t whic s; prop s o. e use i h s y em,

However it may be t d hat heeodedeter- .9: inin elays CD of h syste ar o ne ted.

completion of'the cycle of operation which. theyinitiateor until the pickin up of the lastisteppine l y torin r la SR. ma be aidt 0.1 be a r n d o as. o. e nb d he ize ion thereof, a change in position of anyor; all; the control levers associated therewith and; also to $93 u han llllt l in P q f- 1 E16 the oper t on o h sy em to ansm t hesele h trols has taken-place,

C s der n w that r s m im nl he. presentnew position of controlshas been set up, h e a C s ner iz d as pre iously me hed. a d nasmuch s he Sy tem a e t at. 70,. this time, the energizationof the relay CD eners zes he in relay ST o er a ir fr m ron o a i f e a D e r e ST, to The picking up or relay CD1. also com let s a oir uit o. ic hese e ns l y ir n r). ront. con t 05. t elay QDt.

wire. 20.1,. relay EL. wire 208; ba k n ac 211 q f. relay SA to The line circuit; is norm-ally energized, before e pickin p. or-rela S o a ow e ree o ne eiz io f om: the ba e y wires d. 8,

resistor R wire'li, back contact l6 of relay SA,

wire 21', back contaot- I 9;of relay ST, wire 20, line relay LH, wire 2!; line relay LL, wire 22, back contact23 ofv relay line Wire; 24-, through the several field stations and returning by line wire 25, tov battery 13. However, the energization of relay. ST moves contact IQ of relay ST which is cuit from battery B; wires ll, 65, 66, 61' and 68 front, contact 69; of relay S'I'P, wires H3 and 13,

front contact IQ of relay ST, wire 20, relay LH, wire 2!, relay LL, wire 22, back contact 23 of relay P line wire 24 and returning by line wire 25 to battery B. This high degree of energization is of a duration determined by the dropping of the slow acting relay STP which opens the line circuit at its front contact 69 in as much as this relay STE is de-energized at the back contact 26 of relay ST energized.

The deeenergization of the line circuit drops the. relay LL which energizes the slow acting relay SA through the back contact 28, but the slowv acting characteristics of this relay SA allows the first. step-ping relay (1. to pick up and the code selecting relay CS to be conditioned before the armature of; the relay. SA actually picks up. When the armature of relay. SA does pick up, the line circuit is again. energized for the first impulse as f,ollows:.i'rom battery B, wires l1 and 65, resistor R either shunted or unshunted by the back contact I l. ofrelay CS, wires 12. and I'Lfront contact 14 of relay SA, wires 15.and 13, frontcontact 19 of relay ST, wire 20, relay LH, wire 2|, relay LL, wire 22, back contact 23, of relay P, line wire 24v and returning by line wire25, to battery B.

The circuits efiective to. pick up. the stepping relay (1. and to,condition the code selecting relay CS will later be describedinr connection. with the e planation. of the stepping. relays andin connection with the explanation of the selection of. thedegreeof venergization of impulses.

7 When; the relay. SA picks. up, the following circuit from (-1-), back contact 29 of the last stem iing relay e, wires 3!). and 3|, front contact 3,2 of relaySA, wire 33, frontcontact. of relay ST, wire 35, holding winding of relay ST, to is, completed whichholds. up the, relay ST until the completion of the operating cycle at which,

time it. is dropped. asv later. described. A stick circuit for relay SEL is. also completed by the picking upof relay SA through itsfront contact 88, which is arranged to. complete this stick cir-. cuit before the pick-up circuit for relay. SEL is. brokenat the backcontact 209. It may be said,

that the function of relay SEL is to prevent a ode calloriginating at the control office from conditioning. thestation registering. bank of re.-..

ays; t theoot oto y nt p g he code responsivecircuit at its back contact 210 in as much a his el S may e e er iz d y duringan operating cycle initiated by the con- It will also-be-mentioned herejthat relay SA, is; provided with sufliciently slow acting chars. eete ist es toieee i s arm t r to emain R:

during successive line impulses and only allowing this armature to drop at the end of the cycle of such impulses and thus defines or demarcs the cycle.

The dropping of the line relay LL starts the impulsing means for the line as previously mentioned but before describing in detail this impulsing means it is considered expedient to describe how the degree of energization of impulses is selected to provide distinctive codes.

The selection of the degree of energization of impuZscs.-The present system provides a means for coding the line impulses by selectively shunting or uncovering a series line resistor thereby determining the degree of energization of impulses. In other words, energization may be placed on the line circuit which is effective to operate both relays LH and LL of the system, this being accomplished by shunting the resistor R or an impulse of a low degree may be placed on the line circuit which is efiective to operate only relay LL of the system by removing the shunt on the resistor R The selective shunting of this resistor is accomplished by energizing or de-energizing a code selecting relay CS for each impulse of the line. The condition of the'code selecting relay CS is determined in the first part or station selecting impulses of the cycle by the particular code determining relay CD which is energized and each code determining relay CD is arranged to energize the code busses 36 and 3'! in a manner to pick up or drop the code selecting relay CS according to the position of the jumpers 38 and 39, which positions are different for different CD relays. The circuit effective to condition the code selecting relay CS is shifted from one of these code busses to the other by the picking up of corresponding stepping relays.

It should also be understood that this simple arrangement consisting of only two impulses for station selecting is capable of selecting only three stations and that additional impulses may be employed to select any number of stations obviously requiring additional code busses arranged with distinctive jumper connections as typically illustrated by the busses 36 and 3'! shown herein. After the last station selecting impulse, which in Fig. 1 is the second impulse, the control of the code selecting relay CS is placed on the busses 40, ll, and M respectively to select the energization of the remaining three impulses of the cycle. These busses 40, All, and 42 are energized also by the particular CD relay which is energized and the polarity of such energization is determined by the position of the control levers SML and SGL thus determining the code of the remaining impulses.

In the present system, the conditioning of the code selecting relay CS is performed on the deenergized period of the line, which condition is maintained throughout the suceeding energized period. The relay CS is constructed to operate slightly slower than the stepping relays and consequently upon the first de-energization of the line, as described in connection with the manual starting operation, the first stepping relay (1. Picks up over a circuit to be traced later before the code selecting relay CS is conditioned. With the relay CD energized, the relay CS is conditioned on the first de-energized period of the line over the following circuit from jumper 38, front contact 55 of relay CD wire 46, first station selecting bus 36, front contact 41 of steppingrelay a, wire 48, back contact 49 of stepping relay b wire ba k an impulse of a high degree of V contact 5| of relay 0, wire 52, back contact 53 of relay (1, wire 54, backcontact 55 of relay e, wire 56, back contact 51 of relay LL, wire 58, operating winding of relay OS to a neutral polarity of energy N. w

It is now obvious that the relay CS is energized to open the shunt on the resistor R at its back contact H and select a low degree of current for the first impulse, and this relay CS is held up through a circuit including its front contact 59. This first de-energized period is marked off by the picking up of the relay SA as previously described. However, on the second de-energized period following the first impulse, the second stepping relay b is picked up and the following circuit is completed for positioning the relay CS from front contact 60 of relay CS, wires GI and 62, jumper connection 39, front contact 63 of relay CD wire 64, the second code bus 31, front contact 49 of relay 1), wire 50, back contact 5| of relay 0, wire 52, back contact 53 of relay d, wire 54, back contact 55 of relay e, wire 56, back contact 51 of relay LL, wire 58, operating winding of relay CS to a neutral polarity of energy N. It is obvious that the completion of this circuit causes current to flow in the reverse direction in the operating coil of relay CS thus bucking the effect of the holding current in the stick circuit and effecting the dropping of the armatureof the relay CS which breaks the last traced circuit at its front contact 60 thus interrupting the circuit before the armature can again pick up and resulting in maintaining a de-energized condition of the relay CS.

The second impulse is then made of a relatively higher degree of current in or voltage across the line because the resistor R is shunted by the back contact H of relay CS and thus it can beseen that the coding of each impulse is executed after the picking up of an associated stepping relay on the de-energized period preceding such impulses in accordance with the code'which is selected. In

other words, before the first impulse the picking up of relay a connects relay CS to buss 36, before the second impulse the picking up of relay 1) connects it to buss 31, before the third the picking up of relay 0 connects it to buss 4i), and so on throughout the entire cycle of impulses. Now, keeping in mind this method of determining the degree of energization of impulses, a brief description will be given to the method of applying such impulses to the line at the proper time space interval and to the method of sequentially energizing the relays of the stepping bank of successive impulses.

Impulsing means and operation of the stepping relays.'Ihe impulsing means of the present systemis arranged to apply energy of a preselected degree to the line'circuit for a predetermined time interval termed a conditioning period and then de-energize the line circuit for another predetermined interval termed an executionperiod. Operation of the systemis initiated in a different manner at a field station than at the control office, as will be later described, but regardless of where operation is initiated the starting of an impulsing cycle is always marked by a long deenergized period of the line the end of which period is demarcated by the energization of the slow acting relays SA of the system previously mentioned.

Upon the first de-energization of the line circuit the first stepping relay a, is energized as follows:--from back contact 19 of relay LL, Wire 80, back contact 8| of relay SP, Wire 82 back energized as previously mentioned, the picking up of the first stepping relay a energizes the half step relay SP as followsz-from front contact 93 of relay a, wire 94, back contact 95 of relay 1), wire 96, back contact 91 of relay 0, wire 98,

back contact 99 of relay d, wire I00, back contact IOI of relay 6, wire I02, operating winding of relay SP, Wire I03, front contact I04 of relay LL, wire I05, front contact I06 of relay SA to neutral polarity of energy (N). Relay SP is held up from front contact 88 of relay SA, wires 89 and 90, front contact I09 of relay SP,

'wire I I0, holding winding of relay SP to The relay SP picking up completes the following circuit to pick up the pulsating relay P from front contact I I I of relay SA, wire I I2, front contact I I3 of relay SP, upper'winding'of relay P, wire I I4, front contact I I of relay a, wire I I6, back contact II1 of relay 1), wire Il8, back contact 9 of relay 0, wireI20, back contact I2I of relay 11, wire I22, back contact I23 of relay e to Thus, the line circuit is de-energized by opening the circuit at back contact 23 of relay P and the first conditioning period is completed and the next execution period is begun by dropping of the line relay LL and completing an enervgizing circuit for the second stepping relay 1) as fo1l'ows:-from back contact 19 of relay LL, wire 80, front contact 8| of relay SP, wire I25,

back contact I26 of relay e, wire I21, back contact I28 of relay 0, wire I29, front contact I30 of relay agwir'e I3I, windings of relay b to With the relay b up, the energizing circuit for relay P is broken at the back contact I I 1 of relay b, and the line circuit is again energized on the second impulse through the back contact "23 of relay P. The relay SP is now dropped by reversing the current thereon over a circuit from front contact I 32 of relay SP, wires I33 and I34, front contact 95 of relay (2, wire 96, back contact 91 of relay 0, wire 98, back contact 99 of relay d,

wire I00, back contact IIJI of relay e, wire I02,

operatingwinding of relay SP, wire I03, front contact I04 of relay LL, wire I05, front contact I06 of relay SA to the neutral potential (N). This circuit 'is arranged as the circuit previously described to drop relay CS by neutralization "of currents and so that its own contact I32 interrupts 'the current in the reversed polarity circuit and'its own contact I09 opens the normal'polarity circuit before suchenergycan be efiective to again pick up the armature. V

Thedropping of the relay SP now again energizes the pulsing relay P over a circuit from front contact II I of relay SA, wire H2, back "contact II3 of relay SP, lower winding of relay P, wires I36 and I31, front contact II1 of relay b, wire II 8, back contact H9 of relay 0, wire I20, back contact I2I of relay :2, wire I22, back contact I23 of relay e to ,Thus the line is successively energized and de-energized through the cycle by the picking up and dropping of the pulsing relay P and the stepping relays are successively energized one at a time by alternately picking upand dropping of relay SP.

Statz'dnselectiom-Ihe selection of a particular cycle.

tion-of each impulse is arranged to condition a pilot relay associated with that step, thereby selecting one "station and rendering all others unaffected by the'remaining coded impulses of the In the code employed in this system a choice of a high or a low degree of energization of each impulse gives four different code calls for two steps or impulses, eight different code calls for three impulses and so on, each additional step or impulse doubling the number of possible different code calls. A code table such as the following may be arranged with the present system "by employing two steps thus providing four dif ferent code calls.

Typical code table 'Codc call First step I Second step High energization High energization. High cnergization Low energization. Low-energization High energization. Low energ1zation Low energization.

"the Way irrwhi'ch it is-efiective to select the station will now be considered.

It was previously mentioned that the beginning of the operating cycle is always marked by a tie-energized period of the line which is suffi- "ciently long for the slow acting relay SA at the control office to pick up and this period is effective at each field station to also pick up the SA relay of such field station over a circuit completed atthe 'backcontact I01 of relay LL for the station'shown in Fig. 2. This de-energized period also completes a circuit to start the stepping bank of relays by-energizing the first stepping relay I in Fig. 2 from back contact I39 of relay LL Wire I40, front contact II of 'relay SA wire 142, back contact I43 of relay SP wire I44, back contact I 45 of relay 4, wire I46, back contact I41 of relay 2, wire I48, Windings of relay I to A stick circuit for the stepping relay is also completed from front contact I49 of relay SA wires'I50, I5I and I52,

'to' the stick contacts of the stepping relays.

These stepping relays I, 2, 3, 4, and 5 are sequentially energized one at a'time in the same manner as described in connection with the stepping relays of the control office and the same arrangement is used at each field station of the system.

Inasmuch as the first impulse of the operating cycle under consideration is of a low degree of energization, the relay LH being responsive only to a higher degree of energization is not picked up,;thus completing a de-energized circuit .for the windings of the pilot relay PT as followsz-from back contact I55 of relay LH wire I56, front. contact I51 of relay LL wire I58, front contact I59 of relay SA wire I60, back contact I6I of relay LO, wire I62, back contact I63 of stepping relay 2, wire I64, front contact I65 of stepping relay I, wire I66, through the operating winding of relay PT to negative This circuit leaves the first pilot relay PT in its ole-energized position as shown but when the next stepping relay 2 is energized the second impulse is of a high degree of energization and the relay LI-I is picked up thereby completing an energizing circuit for the second pilot relay PT from front cont-act I55 of relay LH wire I56, front contact I51 of relay LL wire I58, front contact I59 of relay SA wire I60, back contact I6I of relay LO, wire I62, front contact I63 of relay 2, wire I61, through the operating winding of relay P'I' to A stick circuit for these pilot relays may be completed from front contact I49 of relay SA wires I56 and I68, to the stick contacts of each pilot relay, which stick circuit for a picked up pilot relay is completed for the remainder of the operating cycle.

Thus, on the first two steps of the operating cycle under consideration, the first pilot relay PT remains deenergized and the second pilot relay PT is energized at each field station, but it is' obvious that a circuit through the contacts of these pilot relays is completed at one station only inasmuch as the jumper connection I69 is in a different position at each field station. As previously mentioned, the jumper connection I69 at the field station in Fig. 2 is so positioned to render it responsive to the code call previously considered and consequently with the pilot relays thus positioned a circuit which enables the remaining coded impulses of the cycle to position the function relays at this station only is completed as fallows:from (-1-) or as determined by the position of the relay LE contact I55, wire I56, front contact I51 of relay LL wire I58, front contact I59 of relay SA wire E60, back contact I6! of relay LO, wire I10, jumper connection I69, back contact I1I of pilot relay PT wire I12, front contact I13 of pilot relay P'I wire I14 to the contacts of the remaining three stepping relays whereby the function relays SMR, SG and DR are positioned sequentially in accordance with the code of the remaining three impulses.

The picking up of the last stepping relay e opens the previously traced stick circuit for the cycle starting and stopping relay ST at the back contact 29, but inasmuch as the operating cycle is not complete until after the application of the last impulse on the line, a second stick circuit is provided to hold up the relay ST during this last impulse. It will be noticed that the half step relay SP is de-energized during the energization of the last stepping relay 6 and again becomes energized on the next energized period of the line because its circuit is completed at front contact I M of relay e. Therefore a back contact 43 is provided on relay SP to mamtain this stick circuit as followsz-from back contact 63 of relay SP, wire 3i, front contact 32 of relay SA, Wire 33, stick contact 34 of relay ST, wire 35, holding winding ofrelay ST to Thus, it will be noted that the line impulse=following the energization of the last stepping relay 6 opens the stick circuit for relay ST at back contact 43 of relay SP but this impulse continues of the same degree of energization as selected by the code selecting relay CS over the following line circuitz- -from battery B, wires I1 and 65,

resistor R either shunted or unshunted by back contact 1|, wires 12 and 16, front contact I6 of relay SA, wire 21, back contact I9 of relay ST,

wire 26, relay LH, wire 2I, relay LL, wire 22,

back contact 28 of line relay LL and. the line is again completed through its normal circuit as previously traced. It is evident that the slow acting relays SA at each field station also drop during this last impulse and thereby interrupt the stick circuits for all the pilot relays and stepping relays of the system which return all apparatus to a normal at rest condition.

By analogy to the above traced cycle of operation to transmit controls to the. field station it may be readily understood how, by a similar cycle of operation, a field station may register itself at the control office by positioning the pilot relays PT and PT during the first part of the cycle and likewise transmit indications from that station on the remainder of the cycle by positioning indication relays IN, IN and 1N The station registering relays C C and C at the control ofiice are-arranged to be selectively energized according to the positioning of the pilot relays PT and PT and are thus effective to connect the indicating buses I16, I11 and I16 to the proper group of indication relays, there being one group of indication relays at the control office associated with each field station of the systern.

Automatic starting and sequence of communication of station codes.--The above mentioned cycle of operation to transmit indications to the control ofiice may be automatically initiated when the system is at rest by any field station where a change occurs in the occupied or unoccupied condition of the track circuit, the position of the track switch, the indicationof the signals, or the like. Such a change momentarily opens the stick circuit of the change relay.

OH. This arrangement for registering and stor- =i ingla change in condition at the field station is of the type disclosed in the prior patent to D. F. DeLo-ng et al, No. 1,852,402 granted April 5, 1932, and will not herein be considered in detail. However, it may be. stated that the change relay CH and the change storing relay CHS are so arranged that a change in condition at the field station is registered and stored until the system is in condition for an operating cycle to be initiated at that particular station to transmit such new indications to the control ofiice.

It is now obvious that upon the dropping of the change relay CH at a time when the system is at rest or when the'line is normally energized at a steady low degree of energization, a circuit is completed to pick up the relay LO from back contact I16 of relay LH wire I86, front contact E8! of relay LL wire E82 back contact I83 of relay SA wire I64, through the operating winding of relay LO, Wire I65, front contact I66 of the change storing relay CI-IS to Now referring to Fig. 3 and considering that the field station in Fig. 2 is the first field station of the system shown herein, it is obvious that the picking up of relay LO de-encrgizes the line circuit of the systeinbeyond the first station because of the open back contact I56 of relay L0 and the line circuit from this station to the control "office isalso open at present .by'the front contact I81of relay SA The :relay L0 is maintained up during the first de-energizedperiod of the line over a stick circuit from back contact I99 of relay 5, wires I9I and I92, back contact I93 of line relay'LL wires I94 and I95, front contact I96 of relay SAP, wire I 91, stick contact I98 of relay LO, wire I 9.9,.holding winding of relay L0 to The contact 193 of relay LL is constructed to make on a backpointbefore contact I8I of the same relay breaks at its front point thereby enabling the. dropping 'of relay LL to complete this stick circuit before the pick-up circuit for this LO relay is broken at the back contact I8I.

This first de-energized period "of the line also completes a circuit at the control office to pick up the relay ST from back contact 2I I of relay LL, wire 2I2, back contact 2I3 of relay SA, wire2 I4, relay ST to It may be stated here that this contact 2I3 of relay SA is arranged to maintain this circuit until the making of the front contact '32 during the picking up of relay SA.

However, after a predetermined lapse of time .all the slow actingrelays SA of the system are picked up, such as through the back contact I91 of relay LL at the first station, and the line circuit from the control oflice over the wire 24 is completed to this station through relay LH and relay LL wire I98, front contact I54 of relay LO, wire I15, front contact I81 of relay SA wire I38 through either the resistor RF or the back contact I89 of relay CS as determined by the transmitted code call, through the resistor RA and returning to the control ofiice by wire 25. .To maintain the previously traced stick circuit for the LO .relay when the line is energized, a front contact 209 is provided on relay SA which is arranged toshunt the back contact I93 of line relay L'L when energized.

During the first impulse the half step relay SP is energized which establishes a shunt around the front contact I96 of relay SAP over wire 2!, front contact 202 of relay SP wires 203 and I91. This contact 202 of relay SP is effective to complete the stick circuit for the relay LO until the second stepping relay 2 picks up on the de-ener gized period following the second impulse and shunts the contact 292 by a front contact 204 of relay 2. This last stick circuit is maintained throughout the remainder of the operating cycle at which time the relay L0 is de-energized in the same manner as the relay ST at the control ofiice, that is by interrupting one circuit during the de-energized period preceding the last impulse but providing an auxiliary circuit, such. as through the front contact 295 of relay SP which is elfective to maintain the relay LO energized until the application of the last impulse.

In the case that a. plurality of field stations have new indications to transmit to the'control .ofiice, preference is granted to a station in respect to its location in the line circuit. This can .be understood by noticing that the picking up of the LO relay at the station nearest the control .office interrupts the line circuit to other stations m'ore remotely located, thereby preventing subsequent energization of their LO relays because their energizing circuit includes 'a front contact of the associated LL relay which is necessarily de-energized, and further because the line circuit remains open beyond such nearest station.

It is obvious that a condition may exist whereby a plurality of L0 relays may become energized at the beginning of the same operating one to remain energized after the first impulse of, the cycle. This can be seen by considering the stick circuit of the LO relay effective during the first and succeeding impulses of the cycle as was previously described. The relay SP at the nearest station in this case obviously picks up on the first impulse which maintains the LO relay stick circuit through its front contact 232 and on the next de-energized period of the line the second stepping relay 2 picks up to maintain this circuit throughout the remainder of the cycle. However at more remote stations this first impulse does not occur and consequently the above relay operations are not present to maintain their LO relay stick circuits'and consequently they are dropped out as soon as their associated SAPrelays drop. In any event, no stepping will occur at such remote station, because the line circuit is open at a point toward the control office.

General summary.--The characteristic features, method of operation and advantages of the system as a whole can be readily appreciated from the 'foregoing explanation of the 'various individual steps in the operation of the system .of this invention; and it is believed that 'a brief and general description will suifice to make clear the nature of the invention both broadly and specifically.

The communication system of the present invention comprises essentially a two wire circuit energized normally to a comparatively low degree of energization from a source of energy at the control office and extending through each field station of the system; This line circuit, as employed for field station indication purposes, may be shifted by a lock-out relay LO included at each field station to thereby exclude other field stations more remotely located with respect to the control ofiice and at less remote stations such lock-out relay cannot be later picked up, so that -it is not, possible to energize more than one of these LO relays at a time. A series relay LH is included at each field station and at the control office whereby distinction is made between the code of each impulse inasmuch as this relay is arranged to be responsive to only impulses of the higher current value of the two distinctive choices of impulses.

The impulses of this line circuit regardless of their code are effective to sequentially step a bank of stepping relays in a manner quite well known in the art and similar banks of such relays are included at each field station and at the control ofiice. The generation of such impulses is also done in a conventional manner by Venergizing and de-energizing a pulsing relay P located at the control ofiice for each impulse thereby opening and closing the line circuit through a contact operated by this pulsing relay.

During a cycle of impulses initiated at the control office, a series line resistor is either shunted'or uncovered during the de-energization period of the line preceding such impulse to thereby determine the degree of energization of that impulse in accordance with the code call of the particular field station with which commumining the amount of current of each impulse I to thereby establish difierent combinationseach combination being a characteristic code callfor one of said stations and the controls for thatstation, impulse selecting means at each field station for determining the amount of current of each impulse to establish difierent combinations in accordance with the distinctive code call of that station and the indications to be transmitted from it to the control ofiice, and lock-outmeans whereby only one of said impulseselecting means at a field station or at the control office can be effective at one time.

8. In a centralized traific controlling system for railroads, a control ofiice, a plurality of field stations, a communicating circuit extending from said control ofiice to said field stations, means at said control ofiice for applying a series of 'impulses to said communicating circuit; manual initiating means at said control oifice for said impulse applying means, automatic initiating means at each field station for said impulse applying means, and impulse selecting means at said control oflice and each fieldstation operable to determine the degree of current strength of each of said impulses, said impulse selecting means being effective only when the associated initiating means initiates operation of said impulse applying means. I V

9, In a centralized traific controlling system for railroads including a control ofiice, a plurality of field stations and step-by-step mechanisms at said control oflice arranged to be initiated into operation at the control office or at the field stations, a communication circuit normally extending from said control oifice to each of said field stations, means at each field station for shifting said communicating circuit to exclude more remote stations by the initiation of operation of said step-by-step mechanism at that station, and means at each field station for applying difierent combinations of distinctive current impulses on said communicating circuitwhen operation is initiated at that field station said distinctive current impulses being distinguishable by the degree of current strength thereof.

10. In a centralized trafiic controlling system for railroads, a control oflice, a plurality of field stations, a communicating circuit normally conmeeting said control ofiice and all of said field stations, means at said control office for applying time spaced impulses to said communicating circuit throughout a cycle of operation, circuit means at each of said field stations operable to exclude more remote field stations from said communicating circuit during such cycle of operation initiated from that particular station, and current limiting means selectively introducible in the remaining portion of said communicating circuit at that particular station which, initiated that cycle of operation, said means being effective during the-application of each time spaced impulse on said communicating circuit during such cycle, whereby that station which initiated a cycle of operation can be identified in said control ofiice.

ll.-In a centralized trafiic controlling system for railroads, a control ofiice, a plurality of field stations, a communicating circuit extending from said control ofiice to the severalfield stations, means at said control oflice for applying timespaced impulses to saidcommunicating circuit, impulse selecting means at said control oflice operable to determine the resistance of said communicating circuit preceding the application .of

each time-spaced impulse thereof in accordance I with preselected code calls, and station selecting means at each field station selectively responsive to said code calls for selecting the particular oneofsaid field stations corresponding to the particular code call transmitted; I

12. In a centralized traflic' controlling system Q for railroads, a control office, a plurality of field stations, a communicating circuit extending from said control ofiice to the several field stations and normally energized with a low degree of current froma sourceof energy at said control ofiice,

means at said control ofiice for intermittently 1nterrupting said communicating circuit, means at forrailroads, a control oflice, a plurality of field stations, a communicating circuit conductively connecting said control oflice to all of said field stations, impulsingmeans at said control ofiice arranged to intermittently energize said communicating circuit a predetermined plural number of times in eachcycle, means at said control ofiice for selecting the amount of current of each ofsaid communicating circuit impulses according -to: predetermined codes, and code responsive means at each field station arranged each to respond to a particular code to which no other field stationwill respond.

14. Code creating apparatus for creating codes of current impulses each code of which comprises a series of impulses of currents varying in strength comprising, a relay for intermittently at a certain rate energizing a control circuit, and a second relay for intermittently at a varying rate shunting a resistance in said control circuit. 7 15. Code creating apparatus for creating codes of current impulses each code of which comprises a series of impulses of currents varying in strength comprising, a relay for intermittently at a certain rate energizinga control circuit, and a second relay for intermittently at a varying rate shunting a resistance in said control circuit said second relay being picked upif energized by current of one'polarity and being dropped if energized by current of the reversed polarity.

'16. In combination, a circuit connecting a central ofiice and a plurality of field stations said field stations being in series in said circuit, a line relay'for each field station in said circuit, means for normally energizing said circuit by current 1 of low intensity, means for impressing codes upon said circuit at said ofiice and at each of said field stations, means responsive to energization of said circuit by current of high intensity to allow said office' to impress a code of impulses on said circuit,'and means responsive to deenergization of said circuit to allow a field station to impress a code of impulses upon said circuit.

17. In combination with a central oifice and a plurality of field stations, a relay at said central ofiice .and at each field station, a circuit including said relays in series, a lock relay at each field station for opening said circuit at such field station, a second relay at each field station for shunting said circuit toward the central. oflice side of the point of opening at such field station,

and a third relay for impressing a code of imsaid control office for initiating operation of said-l5 communicating circuit interrupting means by ap- 'i aceaeoe pulses on said circuit when said lock relay and said second relay are in their operativeconditions. 18. In combination with'a central office and a plurality of field stations, a relay at said central ofice and at each field station, a circuit including said relays in series, a lock relay at eachfield station for opening said circuit at such field station, a second relay at each field station for shunting said circuit toward the central ofiice side of the point of opening at such field station, means for intermittently interrupting said circuit at said central office, and means for shunting and unshunting a resistance in said circuit at the field station where said lock relay and said second relay are 'in' their active'conditions to cause the series of impulses to refiect a code atsaid central ofiice. l

19. In combination; a control circuit extending from a central office to a field station; a" line relay in said control circuit; a series of neutral type stepping relays; and'means for. causing'said stepping relays to be sequentially picked up one at a I time and one for eachdeenergization ofsaid control circuit including ahalf-step relay which has a second and opposing l relay; said half-step relay having'its pick-up cirtype stepping relays; and

a pick-up circuit; a holding circuit and buckdown stick circuit circuits-fer *sa'idhalfstep relay are'ior'picki-n'g up said half-step relay upon alternate energizations of said control circuit and dropping i-t' on the remaining intermediate energizations of said control circuit.

20. In combination; a control circuit'extending from a central oil-ice to a field station; a line relayin said control circuit; a series of neutral means for causing said stepping relays to be sequentially picked up oneat a time and one for each'deenergization orf'said control circuit including, ahalf steprelay which is picked up upo'nenergization -of' its main winding and when once up stnck'up by-astick circuit including its own front contact, and is caused'to assume its retracted position by energization of winding included in a circuit including its own front contact, for when assuming one position picking up an odd numbered stepping relay and when assuming its other position picking up an even numbered stepping cuit closed upon one energization of said control circuit and having its bucking circuit closed upon the next energization of saidcontrol circuit.

21. A selector system for transmitting, by distinctive codes characterized by a series of impulses of large and small currents arranged in predetermined number of office responsive to a particular one distinctive order, information from a distant field station to a central office comprising; a circuit connecting said ofiice and field station, means at said ofilce for closing and opening said circuit a times for eachcycle of operation of said system,-means at said field station for shunting and unshunting a resistance unit included in said circuit to characterize a 7 code, and'code responsive means at said central of the codes so impressed on said circuit;

22 A selector system for transmitting, by distinctive codes characterized by a series of impulses of large and small currents arranged in distinctive order, information from a distant field station to a central office comprising; a circuit connecting said office and field'station, said oflice for closing and opening said circuit a predetermined number of times for each cycle of operation of said system, means at said field station .for shunting and unshunting a resistance line circuit due to the field. station, a normally office for initially increasing means at unit included in said circuit to characterize a code, and code responsive means at said central ofiiceresponsive to the amount of current flowing during each current impulse to decipher the code of an entire cycle and operate an associated .elec-g, tro-responsive device only when such code is of a predetermined character.

23. In combination with a control oflice and a plurality of field stations, a line circuit extending from-the" control office through the several fie ld='- v stations, means at each field station for shunting andunshunting said resistor at that station in acsaid lock relay at that station is energized, means at each field station for at times energizing said lock relay at that'statio-n, said means being capa- .:bleof loeing initially effective only when said line circuit isunaffected loy'said impulsing means, andz decoding means at said control ofiice responsive to the distinctive changes in current values in said unting or unshunting of said resistors at a particular one'of said field stati'ons while said impulsing means is effective.

:24. cornbination'with a control oifice and a energized line circuit, code transmitting apparatus at said control ofiice and-a-t-said field station, means at said control line when the code transmitting apparatus at said controloifice is to operate, means at said field-station for initially opening said line circuit when-the transmitting apparatus at the field stacordance-with apredetermined code call when zo the current of said 2121011118 to operate, and means at the control oflicd io and at the field station for indicating the different initial line circuit conditions to thereby establish the direction of transmission sothat only one code transmitting apparatus will operate at any .one time. I

' 25. In a centralized trafiiccontrolling system for railroads, a control ofiice and afield station connected by a line circuit, a marginal relay and a sensitive relay connected to said line circuit at applying a series of characteristic impulses to said line circuit, means responsive to said impulses for selectively energizing said marginal and sensitive, relays, a normally inactive code forming "means,

stal'iion, pulsing means at said office for" at said station, a lookout relay at said station means responsive to the'selective energization of said marginal and sensitive relays for operating said lockout relay, and means responsive to the operation of said lockout relay for rendering said code forming means active.

26. In an impulse transmitting system, a loop impulse transmitting circuit, means at one end of said loop circuit for generating and transmitting time spaced impulses of invariable polarity overs.

said circuit, and code transmitting means at the" other end of said loop circuit for varying the intensity of selected ones of said impulses to form codes. I

27. In an impulse transmitting system, a loop impulse transmitting circuit, means at one end of said loop circuit for generating and transmitting time spaced impulses of invariable polarity over said circuit, code transmitting means at both ends of said loop circuit for'varying theinten-ii b therein which conditions are inter-spaced by de-' energized conditions; a series of stepping relays;

me'ans for causing said stepping relays to be picked up sequentially, only one for each of said deenergized conditions; a plurality of local channel circuits sequentially closed by said stepping relays, one for each stepping relay; and electroresponsive means controlled over each channel circuit in accordance with the particular distinctive current condition of said line circuit following the picking up of a stepping relay.

29. In a remote control system, a line circuit connecting a control office and a field station, a source of current for energizing said line circuit, impulsing means in the control ofii'ce only for intermittently opening and closing said line icircuit, step-by-step means in the control oflice and at the field station operated synchronously to take one step for each deenergization of said line circuit, a plurality of devices at the field station, transmitting means .at the field station efiective on each step of said step-by-step' means to distinctively vary the energized condition of said line circuit in accordance with the condition ofone of said devices, and receiving means at the control ofiice effective on each step of said station bystepby-step means to register the distinctive energized condition of said line circuit for that step.

30. In a remote control system, a line circuit connecting a control ofiice and a field station, a source of current for energizing said line circuit,

' impulsing means in the control oflice only for intermittently opening and closing said line circuit, step-by-step means in the control ofiice and at the field station operated synchronously to take one step for each deenergization of said line 'circuit, a device at the field station for each step, transmitting means at the field station efiective on each step of said step-by-step means to distinctively vary the energized condition of said line circuit in accordance with the condition of said .device for that step, an indication device at the control oilice for each step, receiving means at the control ofliceresponsive toeach distinctive energized condition of said line circuit, and circuit means controlled by said receiving means on each step to control said indication device for that step in accordance with the distinctive energized condition of said line circuit. w

31. In a remote control system for transmitting indications from a field station to a control oilice over a line circuit, means at the'control ofiice including a battery source for intermittently energizing and cleener-gizing said line circuit, step-by-step means in the control oilice and at the field station operated synchronously to take one step upon each deenergization of said line circuit, means at the field station governed by its step-by-step means and effective to distinctively vary the energized condition of said line circuit for each step in accordance with the indications to be transmitted, an indication device in the control office for each step, and means in the control ofiice distinctively responsive to'the variations in the energized conditions of said line circuit and effective on each step of said step-bystep means to position said indication device for that step in accordance with the distinctive variation for that step.

I each open condition of said line contact of said control relay tions, and said circuits respectively closed through front contacts of alternate stepping relays; pick up circuits for said stepping relays, each including a contact of said control relay in its other position and a-front contact of the preceding stepping relay,v and said pick up circuits for alternate stepping relays including a front contact of said halfpulses of said seriesto thereby be picked up for y said control relay,

connecting a control ofiice and impulsing means in the intermittently openin'g'and closing said line circontrol oflice, one for each step; "means atthecontrol office efiective on each step 75 'sity of selected ones'of said impulses to form codes, and means allowing only one of said code 32. In a remote control system, a line circuit connecting a control office and a field station,

means wholly in said control office for closing and mitting means at said station for selectively conditioning said line circuit at that station during circuit so as to cause a distinctive energized condition upon the next closure of said line circuit in said central 10 -office, and means in said centraloffice distinctively responsive to each of said distinctive current conditions, whereby indications are transmitted from the field station to the central ofiice .1 with the successive impulses wholly measured in 10 Y the control ofiice.

33. In combination; a control relay operated to opposite positions alternately for a plurality of times in succession; a plurality of stepping relays; a single neutral half-step relay; pick up circuits for said half-step relay, each including a in one of its posistep relay with the remaining including a back 30 contact of said half-step relay; and a stick circuit for said neutral half-step relay closed when it is picked up on aparticular step and maintained closed until the next stepping relay is picked up and said control relay contacts are 35 again in said one position.

34. In combination; a line circuit having a series of time spaced impulses applied thereto; a controLrelay responsive to each successive im- 40 each impulse and to be dropped for each time space a cycle demarking relay responsive to said time spaced impulses so as to be picked up at the beginning of said series and dropped at the end ofsaid series; a series of stepping relays; a single neutral half-step relay;

pick up circuits for said each including a front contact of c and said circuits respectively closed through front contacts of alternate stepping relays; pick up circuits for said stepping relays, each including a back contact of said control half -step relay,

,relay and a front contact of the preceding stepping relay, and said pick up circuits for alternate stepping'relays including a front contact of said half-step relay with the pick up circuits for the intermediate relays including a back contact of said half-step relay; stick circuits for said stepping relays including a front contact of said cycle demarking relay; and stick circuit means for said neutral half-step relay closed when said half-step relay is picked up on a particular step I and maintained closed until the next stepping relay is picked up and until said control relay is again picked up.

:35. In.a.remote control system; a line circuit a field station; a source of. current for energizing said line circuit; control ofiice only for cuit; step-by-stepm-eans in the control oflice and at the field station operated synchronously to take one stepfor each deenergization of said line circuit; a plurality of control levers at the transmitting 'trol' said device for that step was of said step-by-step means to characteristically control the "cdnditien *of the line 'cii' cuit'so ast'o cause a distinctiveenergization of the line oircuit upor'i'the' rlext ensure thereof in accordance with' the position of said control lever"for' th'at step;

a plurali ty of indication devices at the field s'ta tion, 'onefor' eachstep receiving means at-the field staticnresponsive to each distinctive energlZ'atiold 0f Said line circuit; and means'c'ontroned v by said receivingmean's on' ea'ch' step'to' eon in "accordance with the renewing distinctive energizationpfsaid'line circuitu w 36.- In combination, a line circuit having a series of time'spaced impulses applied thereto; a

control relay having contacts operated to'oppo' site positions alternately in response to said series of impulses and time spaces; a pluralityef'stepping relaysja half-steprelay having contacts operableto either of two opposite positions'; means causing said half-step relay to actuate its contacts toan opposite position each time the contacts of said control relay assume oneof' their positions; a pick-up circuit for each odd stepping relay, except the first, including a front contact of the preceding-"even stepping relay, 'a" baek contact of the succeeding even stepping relayfa contact of said half-step relay in one of its-posi tions and a contactof said "control relay in its other position? a pick-upcircuit for each even stepping relay, except the last, including a front contact of the preceding odd stepping relay, a back contact of the succeeding odd stepping relay, said contact of said half-step relay in the other of its positions, and said contact of said' control relay in its other position; and stick circuits for said stepping relays maintained closed until all of said stepping relays are picked up.

3'7. In combination; a line circuit having a series of time spaced impulses applied thereto, a relay repeating said impulses so as to be picked up for each of said impulses and dropped for each of said time spaces; a cycle demarking relay responsive to said impulses so as to be picked up at the beginning of said series and dropped at the end of said series; a bank of stepping relays; a pick-up circuit for each of said stepping relays and each including a front contact of the next preceding relay, said pick-up circuits being divided into two groups, namely, those for the odd numbered relays and those for the even numbered relays; means for successively energizing 7 said pick-up circuits, only one upon alternate operations of said repeating relay and alternately a pick-up circuit for said odd and even groups; stick circuits for each of said stepping relays; and means including said cycle demarking relay for energizing said stick circuits until all of said stepping relays are picked up.

38. In combination; a line circuit having a series of time spaced impulses applied thereto; a neutral control relay responsive to each successive impulse of said series to thereby be picked up for each impulse and to be dropped for each time space; a cycle demarking relay responsive to said time spaced impulses so as to be picked up at the beginning of said series and dropped at the end of said series; a series of stepping relays; a single half-step relay for said series of stepping relays and provided with contacts operable to either of two opposite positions, means including said series of stepping relays for causing said half-step relay to actuate its contacts to opposite positions each time said control relay is picked up; a pick up circuit for each QQ l. tep

i i, v; i ping relay including a front contact of the preceding stepping relays except 'thefirsm a contact of said half-step relay in one of its positions and a' contact of said-"control relay closed-when itis dropped *av'v'ayya pick-up circuitf'o'r each even stepping relay includinga front contact "ofthe preceding'steppingrelay, a contact'of saidhalfsteprelay irf'the dther of its "positions and acon tact orsaid control relay clo'sedwhen it'is dropped away and a' sti'c'kcirc'uit for each of said stepping relays "includinga front* contact of said cycle demarking' relay, said stick'circuits being closed until all of said stepping relays of said series are pidked' 'up. Y r

-39;"In'"'combination, a line circuit having a series of tiniespaced impulses impressed thereonj a control relay for repeating eacli' of' said impulsesand each of "said"time 'spaces, a slow acting relay' 'pickd up "at -the' beginning of said series and dropped at theend'pf said series, a plurality'-of"stepping relayshaving pick-up circuits each including" a""front-' 'contact of the next precedingstepping (relay; a halfstep relay for-alternatelypreparihg' the pickup circuits of 1 the "odd numbered and even numbered stepping re1ays, -'rneans includingsaid control relay for- "actuating said half step relay to anopposite position in -r'esponse to eaeh impulse onsaid line circuitjmeans" including said eon-m1 5 -r'elay I and saw half-step relay for energizing the pick-up circuits of said stepping relays sequentially, one for each time space on said line circuit, and stick circuits for said stepping relays including a front contact on said slow acting relay.

40. In a remote control system, a line circuit having a series of time spaced impulses of selected characters impressed thereon, a plurality of stepping relays and a single half-step relay, means responsive to each time space between successive impulses of a series for causing a separate one of said stepping relays to operate, means responsive to alternate impulses of a series for causing said half-step relay to operate, means controlled by said half-step relay and an operated stepping relay for selecting the circuit of the next stepping relay to be operated, means responsive to the operation of said stepping relays for sequen tially preparing a series of local channel circuits, a series of devices associated with said channel circuits, and means responsive to said impulses for governing each of said devices in accordance with the character of the next impulse impressed on said line circuit following the operation of each stepping relay.

41. In a remote control system, a line circuit having a series of time spaced impulses of selected characters impressed thereon, a line relay in said circuit responsive to all impulses of said series irrespective of their character, a plurality of stepping relays and a single half step relay, means including said line relay effective for each time space between successive impulses of said series for causing a separate one of said stepping relays to operate, means including said line relay effective for alternate impulses of a series for causing said half-step relay to operate, means controlled by said half -step relay and an operated stepping relay for selecting the circuit of the next stepping relay to be operated, means responsive to the operation of said stepping relays for sequentially preparing a series of local channel circuits, a series of devices respectively associated with said channel circuits, and means responsive to each of said impulses on said line circuit for distinctively operating that one of said devices in accordance with the character of the suchimpulse through the medium of that one of said:

relays and a single half step relay, means responsive to each time space between successive impulses of a series for causingra separate one of said stepping relays tooperate, meansresponsive to each impulse of a series for causing said half-step relay to be-ac'tuated to an'opposite position, means controlled by said half-step relay and. an operatedstepping relay for selecting, the

circuit of the next steppingrelay to be operated, means responsiveto the operation of i said stepping relays for sequentially preparing a series of local channel circuits; and'meansresponsive to the next impulse following each-i'operation -of a stepping relay for -selectively"energizing said channel circuit closed by that steppingrelay.

43. In a remote control system, a station, a line circuit having a series of time spaced distinctive impulses on such line circuit, a line relay at said station'distinctively responsive to all impulses of a series on said line circuit, a plurality of stepping relays and a single half-step relay at said station, means responsive to each time space between successive impulses of a series for causing a separate one of said stepping relays to operate, means responsive to each impulse of a series for causing said half-step relay to be actuated to an opposite position, means controlled by said halfstep relay and an operated stepping relay for selecting the circuit of the nextstepping relay to be operated, means responsive to the operation of said stepping relays for sequentially closing a series" of local channel-circuits, and means controlled by the distinctive response of said line relay following each operationof a stepping relay for-energizing a channel circuit closed by the preceding stepping relay.

44; In'a remote control system of the selector type; the combination with a control office and a field station; of a singleline circuit connecting said control oflice *With-said fieldstation; impulsing means only at said control office for energizing said line circuit with a plurality of impulses; code controlling means at said control office and at said field station for determining the character of said impulses, whereby messages are transmitted over said line circuit to and from said field station to said control oifice; and means allowing only one code controlling means to be effective at any one time.

CHARLES S. BUSHNELL. 

